Go grab an XFX 550W or 650W, should be plenty for all your overclocking needs plus it's cheap and top notch quality. Also comes with a 5 year worldwide warranty if you register the product within 30 days.
I'm currently using the 550W for my rig which consists of
- A mothberboard
- FX-8320 @ 4.6ghz
- Radeon R9 270X OC Dual-X graphics card
- 4 sticks of DDR3 RAM
- 1 HDD
- 1 SSD
- 1 Optical drive (DVD burner)
- 1 GbE Network card
- 1 sound card with 2 LEDs
- 1x200mm fan
- 2x140mm fans
- 3x120mm fans / 2 with LEDs
- 1 fan controller with LEDs
- 1 USB laser gaming mouse (G5v2)
- 1 USB gaming keyboard with back-lighting
- 1 USB microphone
- 1 USB 720p webcam (only plugged in sometimes)
.. and on full load, the psu fan is not even audible so there's plenty of power headroom left still